1. Field of the Invention
The invention relates to an image shooting apparatus, an image shooting method, an image shooting program, and a recording medium that records the image shooting program, in particular, to an image shooting apparatus and an image shooting method that extend a depth of field by recovering a blurred image, an image shooting program, and a recording medium that records the image shooting program.
2. Description of Related Art
Previously, in special image shooting apparatuses that extend depths of field, for example, by means of wavefront coding (Wavefront Coding, WFC) of optical apparatuses, image recovery needs to a be performed in a particular design range.
However, if an image shooting distance is separated from a focus location, then a point spread function (PSF: Point spread function, which changes slightly every particular distance) actually applied to an original image deviates from a PSF used for image recovery (using a fixed PSF at the focus location), and therefore maintenance of recovery precision the same as the focus location cannot be implemented. That is, the PSF actually applied to the original image is not fixed due to the image shooting distance, and therefore profile deterioration of a recovered image is generated.
In patent document 1 or patent document 2, a distance is calculated by using a distance detection sensor or multiple image shooting portions, and recovery processing is performed based on PSF data corresponding to each distance obtained by rough estimation.
In patent document 3, a recovery filter that minimizes a mean square error of a frequency domain is designed in consideration of all PSFs corresponding to multiple defocusing locations.
In addition, non-patent document 1 discloses a technology called “auto focus (auto focus, AF)” carried in digital cameras that start to be sold by Panasonic (Panasonic) Corporation since April, 2014. In the technology, a depth from defocus (Depth from Defocus, DFD) of a distance is calculated based on analysis according to a blur quantity; after a distance from two images to a photographed object is calculated, a blur model is derived to make a focus image.
Non-patent document 2 discloses calculation of sharpnesses of images.